[The role of the nasal microbiome in regulating upper airway immune homeostasis]

The nasal microbiome serves as a pivotal regulator of immune homeostasis in the upper airway. Under physiological conditions, it maintains immune equilibrium through mechanisms such as reinforcing the epithelial barrier and modulating innate and adaptive immune responses. Microbial dysbiosis, however, is recognized as a key trigger in the pathogenesis of chronic rhinosinusitis （CRS） and allergic rhinitis （AR）. This review summarizes how the nasal microbiome regulates immune homeostasis by influencing epithelial barrier function and immune responses in both health and disease states, with a focus on CRS and AR. It focuses on the characteristics of microbial dysbiosis and immunopathological mechanisms in CRS and AR, and provides perspectives on microbiome-based diagnostic biomarkers and microecological interventional therapeutic strategies.